Supplementary Cementing Materials for Use in Blended Cements

Provides information on using fly ash, slag, silica fume and natural pozzolans in the manufacturing of blended cements and the effects of these materials on cement and concrete.
Blended cements have been used extensively in Europe but are not common in North America, where supplementary cementing materials are generally added directly to concrete. However, interest in blended cements in North America is growing because of such advantages to the manufacturer as increased production capacity, reduced CO2 emissions and reduced fuel consumption. Blended cements offer a number of potential advantages to the user as well. These include optimized chemistry for sulfate resistance, optimized particle size distributions for low water demand and the desired reactivity, optimized strength gain characteristics, and superior quality control. However, these benefits are not an automatic result of combining clinker with one or more supplementary cementing materials. There is a distinct possibility of making blended cements that are inferior to portland cement if they are not optimized. This report describes the characteristics of the various components that can be used in blended cements and discusses in detail the mechanisms by which they affect each other and the behavior of concrete.By R.J. Detwiler, J.I. Bhatty, and S. BhattacharjaContents1. Introduction2. Materials 2.1 Blended Cement Standards 2.2 Portland Cement Clinker 2.3 Fly Ash 2.3.1 Production and Availability 2.3.2 Definitions and Classifications 2.3.3 Characterization 2.3.4 Need for Improved Specifications 2.3.5 Reactivity 2.3.6 Processing of Fly Ash 2.4 Blast Furnace Slag 2.4.1 Production 2.4.2 Availability 2.4.3 Characterization 2.4.4 Specifications 2.4.5 Reactivity 2.4.6 Processing 2.5 Condensed Silica Fume 2.5.1 Production 2.5.2 Characterization 2.5.3 Availability 2.5.4 Specifications 2.6 Natural and Manufactured Pozzolans 2.7 Limestone 2.8 Rice Husk Ash 2.9 Cement Kiln Dust 2.10 Supplementary Cementing Materials 2.10.1 Pozzolanic properties 2.10.2 Physical effects 2.10.3 Possible impurities3. Behavior of Cement and Concrete Containing Supplementary Cementing Materials 3.1 Workability 3.1.1 Rheology 3.1.2 Effect of Fly Ash 3.1.3 Effect of Slag 3.1.4 Effect of Silica Fume 3.2 Setting and Hydration 3.2.1 Hydration of Cement 3.2.2 Effect of Supplementary Cementing Materials 3.2.2.1 Slag 3.2.2.2 Fly ash 3.2.2.3 Silica fume and rice husk ash 3.3 Compressive Strength 3.3.1 Effect of Supplementary Cementing Materials 3.3.2 Silica Fume 3.3.3 Slag 3.3.4 Fly Ash 3.4 Volume Changes 3.4.1 Plastic Shrinkage 3.4.2 Drying Shrinkage 3.4.3 Soundness 3.4.4 Creep 3.5 Durability 3.5.1 Pore Structure and Permeability 3.5.1.1 Curing at normal temperatures 3.5.1.2 Curing at elevated temperatures 3.5.2 Sulfate Resistance 3.5.3 Carbonation 3.5.4 Corrosion of Reinforcement 3.5.4.1 Mechanism of corrosion in concrete 3.5.4.2 Effect of supplementary cementing materials on corrosion 3.5.5 Alkali-Silica Reactivity 3.5.6 Frost Resistance 3.5.6.1 Mechanisms 3.5.6.2 Effect of silica fume 3.5.6.3 Effect of fly ash 3.5.6.4 Effect of slag 3.6 Interaction with Chemical Admixtures 3.6.1 Water Reducers 3.6.2 Air-entraining Agents 3.6.3 Set-controlling Admixtures4. Optimization 4.1 Background 4.2 Blended Cement Standards 4.2.1 Prescriptive vs. Performance 4.2.2 Building Acceptance 4.3 Obtaining the Desired Properties 4.3.1 Strength and Strength Gain 4.3.2 Durability 4.4 Applications 4.4.1 Checklist for Establishing Criteria 4.4.2 Pavements 4.4.3 Marine Structures 4.4.4 High-rise Buildings 4.4.5 General-use Cement5. Conclusions and Recommendations

Water Resources Systems

ISO FDIS 19906:2009 Petroleum and natural gas industries — Arctic offshore structures

This International Standard specifies requirements and provides recommendations and guidance for the design, construction, transportation, installation and removal of offshore structures, related to the activities of the petroleum and natural gas industries in arctic and cold regions. Reference to arctic and cold regions in this International Standard is deemed to include both the Arctic and other cold regions that are subject to similar sea ice, iceberg and icing conditions. The objective of this International Standard is to ensure that offshore structures in arctic and cold regions provide an appropriate level of reliability with respect to personnel safety, environmental protection and asset value to the owner, to the industry and to society in general. This International Standard does not contain requirements for the operation, maintenance, service-life inspection or repair of arctic and cold region offshore structures, except where the design strategy imposes specific requirements (e.g. 17.2.2). While this International Standard does not apply specifically to mobile offshore drilling units (see ISO 19905-1), the procedures relating to ice actions and ice management contained herein are applicable to the assessment of such units. This International Standard does not apply to mechanical, process and electrical equipment or any specialized process equipment associated with arctic and cold region offshore operations except in so far as it is necessary for the structure to sustain safely the actions imposed by the installation, housing and operation of such equipment.

ISO 19901-1:2005 Petroleum and natural gas industries - Specific requirements for offshore structures — Part 1: Metocean design and operating considerations

This part of ISO 19901 gives general requirements for the determination and use of meteorological and oceanographic (metocean) conditions for the design, construction and operation of offshore structures of all types used in the petroleum and natural gas industries. The requirements are divided into two broad types:
a) those that relate to the determination of environmental conditions in general, together with the metocean parameters that are required to adequately describe them;
b) those that relate to the characterization and use of metocean parameters for the design, the construction activities or the operation of offshore structures.
The environmental conditions and metocean parameters discussed comprise
⎯ extreme and abnormal values of metocean parameters that recur with given return periods that are considerably longer than the design service life of the structure,
⎯ long-term distributions of metocean parameters, in the form of cumulative, conditional, marginal or joint statistics of metocean parameters, and
⎯ normal environmental conditions that are expected to occur frequently during the design service life of the structure.
Metocean parameters are applicable to
⎯ the determination of actions and action effects for the design of new structures,
⎯ the determination of actions and action effects for the assessment of existing structures,
⎯ the site-specific assessment of mobile offshore units,
⎯ the determination of limiting environmental conditions, weather windows, actions and action effects for pre-service and post-service situations (i.e. fabrication, transportation and installation or decommissioning and removal of a structure), and
⎯ the operation of the platform, where appropriate.
NOTE Specific metocean requirements for tension leg platforms are to be contained in ISO 19904-2[1], for sitespecific assessment of jack-ups in ISO 19905-1[2], for arctic structures in ISO 19906[3] and for topsides structures in ISO 19901-3[4].

Modelling and Computation in Engineering